The invention relates to a system for use in the delivery of a material into the body of a mammal and a method of using such a system. More particularly, the invention relates to a system for use in delivering a shear-sensitive injectable material into the body of a mammal to bulk-up, augment, or replace tissue.
Shear-sensitive injectable materials have a variety of medical applications. These materials may be used as bulking agents to strengthen tissues weakened by old age and/or disease, as implants to contour overlying tissue (e.g., in plastic surgery applications), or as prosthetic implants, acting as replacement tissue. In some instances, it is desirable to use a shear-sensitive injectable material as an embolic, for example, in the occlusion of abnormal blood vessels. Typical shear-sensitive injectable materials comprise a cross-linked polysaccharide or hydrogel, a carrier (typically a hydrophobic material such as oil), and matrix materials, providing paste-like compounds useful to bulk up tissue.
Current methods and delivery systems for delivering shear-sensitive injectable materials to a tissue, or to a space adjacent to a tissue, have certain disadvantages. A typical delivery system used is a syringe comprising a tube and a plunger. During the injection process, the carrier/hydrophobic material has a tendency to separate from the matrix material within the tube of the syringe, resulting in carrier-only injection into a tissue. Separation may be caused by a number of factors including shelf-life, material separation, excessive pressure in the syringe applied by the plunger, pushing the carrier/hydrophobic material ahead of the matrix material, or the use of an injection needle having a diameter which is too small. When a carrier is not well mixed, the matrix material is difficult to advance through the syringe with the plunger. Ultimately, the physician is unable to gauge properly the amount of bulking material he or she is actually injecting, resulting in the necessity for multiple treatments and discomfort to the patient.
It is an object of the present invention to provide a system for delivering a shear-sensitive injectable material. As defined herein, a xe2x80x9cshear-sensitive injectable materialxe2x80x9d is a material which comprises components, or is itself a component, which is subject to shear (e.g., causing degradation or a change in viscosity) upon mixing and passage through a standard-sized needle (e.g., about 10 gauge to about 25 gauge). In the process of mixing, shear-sensitive injectable materials form paste-like compounds which are ideal for implantation into the body because they conserve their volume and do not migrate far from a site of injection. Such materials are useful in applications to bulk-up, augment, or replace tissues.
The present invention relates to a delivery system for delivering a shear-sensitive injectable material into the body of a mammal, such as a human being. The delivery system acts as a mechanical feed which continuously mixes a shear-sensitive injectable material as it delivers the shear-sensitive injectable material to a target tissue, or to a site adjacent a target tissue, within the body of a mammal. In one embodiment of the invention, the delivery system is composed of an injector system having a rotatable mixing member coupled to a driving system.
The injector system comprises an injector housing defining a lumen and having an output end coupled to a needle assembly for coupling to a needle and a driving system connection end for coupling to a drive mechanism. A mixing member extends within the lumen of the injector housing from the driving system connection end of the housing to at least the output end, and is rotatable within the lumen to feed the shear-sensitive injectable material out through the output end through the needle assembly. In a further embodiment of the invention, the injector housing comprises a feeder and a reservoir; the reservoir coupled at one end to the feeder and at the other end to a needle assembly. In this embodiment, the mixing member rotates within the feeder to feed a shear sensitive injectable material into the reservoir and moves linearly within the reservoir portion to push the shear-sensitive injectable material through the needle assembly.
A driving system is provided for use with the injector system. The driving system includes a drive mechanism in communication with an actuator which is capable of actuating the drive mechanism. An interfacing member is coupled to the drive mechanism and is for coupling to the mixing member of the injector system. In operation, the driving system is coupled to the injector system via the interfacing member. Actuation of the drive mechanism causes the mixing member to rotate within the lumen of the injector housing, thereby to mix and deliver a shear-sensitive injectable material within the injector housing through the output end of the injector housing to an injection site. In one embodiment of the invention the actuator comprises a switch and is coupled to an energy source, such as a battery, which is in electrical communication with the drive mechanism.
In another embodiment of the invention, the injector system is loaded with a shear-sensitive injectable material and is provided within a packaging to maintain the sterility of the injector system. In this embodiment, the injector system is ready to be coupled to the drive mechanism of the driving system and to be injected into the body of a mammal.
In yet another embodiment of the invention, a coupling system is provided for coupling to a tube of a syringe. The coupling system adapts the tube of the syringe to deliver a shear-sensitive injectable material into the body of a mammal. The coupling system has a coupling housing capable of mating with the tube of the syringe. A drive mechanism is positioned within the coupling housing and is capable of providing a rotary force upon actuation by the user. The coupling system also includes a mixing member which is for coupling to the drive mechanism and which extends within the tube of the syringe when the coupling housing is mated to the tube of the syringe. Upon actuation of the drive mechanism, the mixing member rotates in response to rotary force from the drive mechanism. The rotation of the mixing member simultaneously mixes and delivers a shear-sensitive injectable material loaded within the syringe. In some embodiments of the invention, the coupling housing further comprises an actuator for actuating the drive mechanism. In yet other embodiments of the invention, the coupling housing comprises finger grips for ease of manipulation of the housing and tube of the syringe during the injection process.